Method of heating



Feb. 11, 1936. Q A, R055 2,030,543

METHOD of* HEATING Original Filed Nov. l5, 1927 2 Sheets-Sheet l Feb. 1l, 1936. O, A ROSS 2,030,543

METHOD OF HEATING Original Filed Nov. -l5, 1927 2 Sheets-Sheet 2 0 202 20M 20s-T 7 45 INVENTOR Cil Patented Feb.` 11,1936

PATENT OFFICE METHOD. F HEATING 0scar A. Ross, New York, N. Y.

Application November 15, 1927, Serial No. 233,482

' Renewed September 13, 1934 zo claims. (ci. 237-12) This invention relates to heating systems and more particularly to major heating systems employed in large buildings wherein extensive radiation is installed.

One object of this invention is to furnish a major heating system wherein a number of comparatively small buildings, or a number of sections of a large building may have steam, or other heating iiuid, supplied thereto in sequential order,

in this manner reducing the maximum supply of steam, generally termed maximum demand to a comparatively small amount, as compared to the maximum demand required if all the small buildings, or sections of the large building were supplied with the steam simultaneously.

Another object is to furnish a heating system wherein the aforesaid sequential supply of steam will be eiected automatically as well as in accord with the outside temperature whereby 9 the buildings, or sections, will be uniformly heated irrespective of variations of said outside temperature. l l I The invention in one of its embodiments is adapted for use in systems wherein condensate from a steam heating system is utilized for heat-l ing water supplied to hot water service pipes. The invention is also adaptable to heating systems for comparatively high buildings wherein the steam supplied to the system maybe fed through risers at a comparatively high temperature to the point of distribution at an upper lpart of the building and thereafter reduced in pressure for supply to the radiators, in this manner permitting the use of comparatively small risers and reducing the condensation losses therein.

Other objects and advantages will appear las the description of the invention progresses and the novel featuresthereof will be pointed out in the appended claims. ,y

The invention consists in such novel features,

` arrangements, combinations of lparts and methods as are described in connection with the apparatus herein disclosed by way of example only. Novel features and ycombinations of the apparatus are disclosed and claimed in nur copending divisional application Ser. No.,757,790, filed December 17, 1934. Other features, embodiments and combinations of the apparatus are disclosed and claimed in my copending application Ser. No. 515,761, filed February 14, 1931, comprising a continuation of my copending application Serial No. 56,283, filed September 14, 1925.

' In describing the invention in detail, reference is had to the accompanying drawings, illustrating embodiments of the invention, and wherein like characters of reference designate correspond-j perspective view of a portion of the apparatusv associated therewith; Fig. 3 is a sectional view of another part of said apparatus; Fig. 4 is a diagrammatic view of still another-part of .the apparatus; and Fig. 5 isa modiiiedform of heat- 5 ing system shown diagrammatically.

Referring to Fig. l, the building I is divided into three heatedsections, 2, 3 and 4,-each section having rooms a,`b and c supplied with a radiator 5, having thermally controlled outlet valve 6, except room 2a which is preferably supplied with a hot water radiator 8 receiving hot water from boiler 30 through riser 8a and discharging said water through return 8b. The radiators 5 in section 2 are fed by riser 9,. those of section 3 15 by riser IU and those of section 4 by riser I I. The condensation from said radiators is returned from section 2 by return I2,\from section 3, by return I3 and from section 4 by return I4, said risers and returns being connected to sequential ydistributing 20 lunit I5, each return 'having a trap IB-at the discharge end thereof. Each heated section 2, 3 and 4, forms a subsidiary heating system of the majo system supplying heat to building I.

Steam is assumed to be supplied from a public utility service main .I1 through pipe I 8 and thence to valve I9, meter 20, reducing valve 2|, automatic cutout 22, and valve 23 to sequential distributing unit I5. The condensation from returns I2,- I3`and I4 passes through traps I6, unit I5 and 30 pipe 25 to pump 26 of known form for removing air, or vapors, thence throughpipe 21, pressure check valve 28, heating coil 29 of boiler 30, pipe 3| having pressure check valve 32 and water meter 32a and thence to sewer 33.

The hot water heating boiler receives water from service main 34 and distributes hot water to faucets 1 through risers 35. f ,f

Traps I6 have a common air and vapor withdrawal line 36 connected to the vacuum end of 40 the air discharge section of pump 26, the air being discharged to sewer 33 through pipe 31.

Over-heat" thermostats 38 in sections 2, 3 and 4, are connected in multiple and arranged to energize automatic cut-off valve 22 for cutting 45 off the steam supply upon any abnormal heating of said sections, a switch 39 manually controlling the ow of energy to wires40, 4I and 42 of the circuit controlling said valve.

Referring to Figs. 2 and 4, showing sequential 50 distributing unit I5 in more detail, motor 45 drives worm 46 engaging gear 41, mounted on shaft 48, also secured toy which are distributor cams 2s, 3s and 4s and return cams 2r, 3f and 4r. The cam faces 49 of cams 2s, 3s and 4s are adapted to 55 depress valve stems 50 thereby opening supply valves 2st, 3sv'and 4sv. The camfaces 5| of cams 21', 3T and 4r are adapted to depress valve stems 52 thereby opening return valves .2111, 3ro and 4rv. Valve stems 52 each support a contact spring 53 adapted to contact with a'. contact 54 and establish the pump motor circuit as follows: from positive energy to switch 59, wire 55a, motor 55, wire 56, pipe 25, a contact 53 in lowered position, contact 54, wire 51 and switch 58 to negative energy. Referring to Fig. 4, gear wheel 41 preferably formed of insulating material, supports contact sector 62 substantially encircling the side thereof, the Contact springs 63 and 64 bearing thereon, a sector space being provided sufficient to permit the opening of the circuit to motor 45 when spring 64 enters such space.

Located in the outside atmosphere, preferably on top of building is thermostatic device 10, more fully described in my said copending application Serial No. 56,283, filed September 14, 1925, and Ser. No. 515,761, led February 14, 1931, the rheostat arm 1| lowering to cut out resistance 13 upon the lowering of the outside temperature and raising to add resistance upon the increase of said outside temperature. Said device controls the thermostat control` circuit as follows: from positive energy` to wire 15, arm 1|, a contact 12, resistance 13, wire 16, night switch 11, wire 18, motor 14, to negative energy through wire 19, in this manner varying thespeed of motor 14 proportionately to the variation of the outside` ternperature. tact drum 84, supporting contact 85, adapted to momentarily bridge contact springs 86 and 81.

-Motor 45 rotates cams 2s, 3s, 4s, and 2r, 3T, and 4r through one heating cycle by establishment of the heat supply circuit as follows: from positive energy to wire 66, contact spring 63, contact 62, contact spring 64, Wires 61, 68, motor 45 and wire 69 to negative energy.` Aftery gear 41 has completed a revolution in the direction shown by the arrow, contact spring 63 will enter space 65 thereby opening said circuit and motor 45 will stop. The relation of the space 65 and the various cams is such that motor 45 stops just after cam 4s has permitted valve 4st to close and before valve 2sv is again opened. Likewise cam 4r permits the closing of valve 41'v and said motor stops ,before valve 2111 is again opened. After motor 45 has stopped, no flow of steam to, or flow of condensation from the system occurs and said motor remains stopped until contact 85 again bridges contact springs 86 and 81, whereupon the frequency circuit is established as follows: from positive energy to Wire 90, contact spring 86, contact 85, contact spring 81, wires 9|, 68, motor 45 and Wire 69 to negative energy. As soon as motor 45 has again started contact 62 bridges contact springs 63 and 64 and energy is thereafter.A

supplied from wire 66. r y

It is to be noted that each one of the contacts 12 has a dial indicating temperature of the outside atmosphere, and if desired the rod 10a and spring 10b may be removed and arm 1| operated manually from handle 10c.

Itis also to be noted that when the atmosphere has reached the arm 1| will move to the uppermost contact 12 to open the circuit to motor 14. If for any reason the arm should move onto said l contact and motor 14 should stop with contact bridging both springs 86 and 81, motor 45 would continue to operate for producing minimum heating. To avoid this unnecessary operation a contact spring 85 is arranged to engage contact 85 simultaneously with contact 86 whereby the fclearlng circuit is established Aas follows: from positive energy to wire 80, contact spring 86, con- Motor 14 drives worm 83, rotating contact 85, contact spring 85, wires 96 and 18 to motor 14 and thence through Wire 19 to negative contact spring 86, in this manner also cutting off energy to motor 45 through Contact' spring'81.

Referring to Fig, 3, trap I6 comprises tank |00 provided with cap 0| supporting corrugated diaphragm |02, the interior of which communicates with passageway |03 and pipe36, also check valve |04 constrained to seat by spring |05 permitting vacuum pipe 36 to withdraw air and vapors from the heating system through chamber |06 of tank |00, at the same time creating a partial vacuum within diaphragm |02, whereby iioat |01, and valve |08 secured thereto and to said diaphragm, will be raised to empty trap- 6. Valve |08 is biased in both extreme upper and lower positions by weight |09 secured to one arm of .bell crank H0, the other arm of which is pivoted to oat |01. The chamber containing diaphragm |02 is open to atmosphere through opening The operationof the trap is as follows: during the 'oif heating period of a section, as for example section 2, practically all the condensation collects in tank |00. As cam 2r acts to open valve 2rv and also starts pump 26, the vacuum produced by said pump causes a partial vacuum in the diaphragm- |02, also raises valve |04 and creates a partial vacuum in the pipe lines and radiators of section 2, it being assumed that the radiators 5 have cooled sufficiently to open valves 6. As tank |00 will contain considerable condensation, the combined efforts of iioat |01 and diaphragm |02 will cause valve |08`to rise whereupon said condensation will iiow to pump 26 and thence to heating coil 29 of hot water heater 30, said pump separating all air and vapors therefrom, passing the water only to said heater. After tank |00 has been emptied and pump 26 stopped, the air leakage back through said pump will nullify the vacuum in pipe 36 and diaphragm |02, thereby again permitting Valve |08 toseat and seal the return line preparatory to the next heating cycle and resulting condensation produced thereby.

Referring to Figs. 1, 2, 3 and 4, the operation of the system disclosed thereby is'as follows: assume the outside temperature surrounding building to be approximately 40 under which condition at a frequency whereby the resulting heat supply periods will be rendered at suiilcientlyl close intervals to adequately heat building with-an exterior temperature of approximately 40.

After contact 85 has established the heat supply circuit and before gear 41 has rotated to again open said circuit as heretofore described, contact 85 will have moved suflieiently to have opened said circuit between contact springs 86 and 81, and as space 65 of gear 41 passes under contact spring 64, motor 45 will stop in' a manner to maintain all the supply valves 2r, 3f and 4r closed until contact 85 again bridges contact springs 86 and 81.

If the outside temperature reaches 70 or higher, and at Which'tixne no artificial heatis required in building the arm 1| moves to the 70 contact whereupon the energy to motor 14 is cancelled by device 10, thereby also stopping the motor 45 indefinitely.

If the outside temperature falls to 10, arm 1| energy. With this circuit established motor 14 operates until contact 85 has moved away from.

Cil

moves to the contact 'I2 whereupon motor 14 operates at maximum speed thereby producing a maximum number ofheating cycles by increasing the frequency thereof.

During each heating cycle produced by -establishing the heat supply circuit, and as motor 45 starts, cam 2r acts to open valve Zrv and drain section 2 of all condensation, thereafter the steam from pipe I8 is supplied to 'the subsidiary heating system of section 2 by action of the raised portion 49 of cam 2s in opening valve 28u, said valve being maintained in open position for a period of time sufficient to ll all the radiators in section 2 with steam as well as maintain pressure thereinl until the radiator structure has attained a temperature substantially equivalent to that of the steam, whereupon said valve is closed.

A comparatively small interval of time after valve 2st has closed, the raised portion 49 of cam 3s acts to openv valve 3sv whereupon steam is supplied to radiators 5 of section 3 and after the subsidiary system therein'- has been filled with steam, the cam portion 49 of cams acts to open vvalve 48o whereupon steam is supplied to the subsidiary system in section 4 andas said last named raised portion 49 acts to close valve 4st, the space 65 will have passed under contact spring 64 and motor 45 will be stopped with the raised portion 49 of cam 2s in a position to again effect the opening of valve' 2st. From the foregoing it will be noted that the steam has been supplied to the sections 2, 3 and in sequential order during each heating cycle.

Substantially simultaneously withv the opening of valve 23o, as described, the raised portion 5l of cam 2r will have passed away from valve stern 52 of valve Zrv thereby closing said valve. As described, when valvey stem 52 is lowered and contact spring 53 engages contact 54, the valve Zrv is opened and pump 26 is started thereby draining trap I6 of condensation as well as establishing a partial vacuum in the subsidiary system of section 2, and as supply valve 2sv opens, steam from supply pipe I8 will quickly ll said system, the thermally controlled valves 6 preventing the steam from entering the return I2 until the condensation thereof is effected.

A predetermined interval of time before cam 3s acts to open supply valve 3st, the cam 31' will act to open return Valve 3ro whereby trap I6 in return line I3 will be drained of its condensation and a partial vacuum will be established in the radiators 5 and risers I0 of section 3 pior to the opening of supply valve Ssvy by cam 3s.

A similar-sequence of operations will occur in draining condensation from and supplying steam to the subsidary heating system of section 4 and thereafter motor 45 will stop until another heating cycle is initiated by establishing the heat supply circuit by contact 85.

From the foregoing it will be noted that by sectionalizing a building as I, for heating purposes, and supplying steam to a subsidiary heating system in each section sequentially, a comparatively small maximum demand of the steam is required thereby reducing the yearly maximum demand charge usually made by the con- 'cern supplying said steam.

The number of subsidary heating systems and the radiation therefore is preferably proportioned whereby during the coldest weather, and upon the.completion of a heating cycle, the drum 84 will have made a complete revolution and contact; 85 will again establish the heat supply circuit, in this manner producing a substantially continuous supply of heat to building I, the supply calling for a comparatively low maximum demand. from the source.

It is to be noted that the subsidiary heating systems of sections 2, 3 and 4, may be employed to heat detached buildings, one of the buildings containing the distribution apparatus I5 and auxiliary devices therefor. I v In certain buildings where a comparatively small quantity of hot water is required, the surplus hot water from boiler 30 may be supplied to a hot-waterradiator 8 in room 2a, the cam 2s lbeing adjusted to supply a proportionately lesser quantity of steam to the heating system in section 2.

Whereas pipe 36 connects the vacuum side of pump 26 to all the traps I6, the partial vacuum established in diaphragms |02 will not be suflcient to raise the valve |04 in other than the selected trap in, which the condensation acting -on the float will effect the raising of said valve.

Traps I6 are preferably of a capacity whereby substantially all the condensation from their correlated section, as 2, 3 or 4 will return thereto before float I 01 will rise with the assistance of by arm 68h insulatively supported by Aarm II and 'arranged to be shunted by switch 68e may be placed in series with motor whereby said motor is slowed do-wn as the outside temperature is lowered, in this manner effecting comparatively longer supply periods of the steam to each section during each heating cycle, such longer supply periods; under certain conditions, being required to compensate for the more rapid cooling of the radiato-rs during colder Weather.

v At night or at other non-working hours when it is desired to maintain a lower temperature in the building,` night switch 'l1 is opened, thus throwing resistance 80 into the circuit of motor 14. This results in this motor operatingl at a lower` speed, thus increasing the time interval between heating periods.

Whereas the raised cam faces 49 and 5I are shown as of a definite length, they may be made of variable length as shown in the Patent 1,178,170 to Marks, April 4, 1926.

The cam faces 49 of supply cams 2s, 3s and 4s are preferably formed whereby the valves' 251.1. 381) and 4st opened thereby will remain open for a period suficient toll all the radiators as well as insuring that the radiator structure will assume a temperature substantially that of the steam therein.

The cam faces 5I of return cams 2r, 3f and 4r are preferably formed whereby the valves 21'11, 3ro and 411; are opened for a period of time sufcient to drain all the condensation from their correlated traps I6 and also permit the forming of a partial vacuum in the returns and radiators whereby rapid lling thereof occurs when the supply valves are opened.

Wh-ereas the building I has been shown as sectioned in vertical planes, comparatively high condensation therein as Well as reducing the cost of installation.

Whereas vone return pump as 26 has been shown for controlling all the' ilow of condensation, a similar pump may be employed for each section 2, 3 and 4, for independently controlling the flow of condensation thereform and establishing the partial vacuum therein.

Whereas-the steam supply has been shown as a public utility service main, a suitable steam boiler may be employed therefor.

Referring to the modied'form'of heating system shown in Fig. 5, the thirty-six story building 200, having basement 20|, is shown as sectioned in horizontal planes A to J, each section being assumed to contain four iioors IJ, 2J, 3J and 4J, each iioor having a, heat radiating system 202 forming a portion of the subsidiary heating system supplied with low pressure steam from feeder line 2I0, said line receiving steam from high pressure riser" 203 through reducing valve 204, each syst-ein being drained by a return 205.

In this major heating system, the subsidiary heating system of each section A to J is preferably supplied With independent condensation and vacuum pumps 26 arranged to establish a partial vacuum in each subsidiary system just prior to the supply of the steam thereto.

Comparatively high pressure steam from public utility service main Il, or from high pressure boilers, is fed through distributing device 201 and through risers 203. to the reducing valves 204,

thereby permitting the use of comparatively small j e risers and reducing condensation.

The reducing valves 204 form the origin of the low pressure distribution to the subsidiary systems from whence the steam and condensation is down-fed through feeder line 2I0 and radiating system 202 to returns 205.

Owing to the larger volume of steam in the longer risers, as 2031-1 and 203J, the distributor cams 49 of unit 20'?, are preferably formed to effect comparatively shorter time intervals of opening the supply valves as 23e, than the similar cams opening similar valves to the risers 203A and 203B, thereby equalizing the supply of steam by permitting the high pressure steam of the longer risers to expand into the subsidiary systems through the reducing valves 204.

Steam distributing unit 201, is similar to unit I5; being modified to include a larger number of supply and discharge valves, as `2sv and 21o and correlated cams and circuit closers therefor.

A pipe 208 connecting each trap and correlated pump 26 replaces the pipe 36 commonly connected to all the traps l of Fig. l, and a pipe 209 commonly connected to all the air outlets of the pumps 26 conveys the air and vapors discharged thereby to the sewer 33.

While the invention has been described with respect to certain particular preferred embodiments which give satisfactory results, it will b'e understood by those skilled in the art, after understanding the invention, that various changes and modiiications may be made without departingfrom the spirit and scope of the invention, and it is intended therefore in the appended claims'to cover all such changes and modications.

I claim:

1. The method of supplying heat from a source to a plurality of subsidiary heating systems forming a major heating system arranged to heat a plurality of enclosed spaces which involves, establishing a ilow of the heat from the source to each subsidiary system for one period of time alternately with cancelling the ilow for another period of time, the flow periods being established to each subsidiary system at predetermined successive time intervals and the time interval of the nonow periods being suihciently long to permit completing the heat flow period to the last subsidiary system before again establishing the heat ow to the rst subsidiary system.

2. The method of supplying heat in cycles from a source to a plurality of subsidiary heating systems forming a major heating system arranged to heat a plurality of enclosed spaces which involves,

establishingftimed ovvs of heat from the sourceto each subsidiary system successively during each heat cycle and varying the frequency of the cycles in response to the variations in temperature of atmosphere outside the spaces.A

3. Thea method of supplying heat from a source to a plurality of subsidiary heating systems forming a major heating system arranged to heat a plurality of enclosed spaces which involves, successively establishing flows of heat from the source to each subsidiary system during one period of time alternately with cancelling the heat flows thereto during another period of time and Varying the time interval of the heat flow periods in response to the variations in the temperature of atmosphere outside the spaces.

4. The method of supplying heat from a source to a plurality of subsidiary heating systems forming a major heating system arranged to heat a plurality of enclosed spaces which involves, successively establishing flows of heat Afrom the source to each subsidiary system during one period of time alternately with cancelling the heat flows thereto during another periodof time and varying the time interval of the non-dow periods in response to the variations in temperature of atmosphere outside the spaces.

5. The method of supplying heat in cycles from a source to a plurality of subsidiary heating systems forming a major heating system arranged to heat a plurality of enclosed spaces `which involves, successively establishing timed flows of heat from the source to the subsidiary systems during each cycle and simultaneously varying the length of time of the timed ilow periods and the frequency of the cycles in response to variations in temperature of atmosphere outside the spaces.

6. The method of supplying heat from a. source to a plurality of subsidary heating systems forminga major heating system arranged to heat a plurality of enclosed spaces which involves, successively establishing timed flows of heat from the source to the subsidiary systems alternately With cancelling the iiow thereto, the cancellation of the ow period to one subsidiary system being effected before the establishment of a flow period to a succeeding subsidiary system.

7. The method of supplying steam in cycles from a source to a steam heating vsystem for heating one or more enclosed spaces which inv'olves, draining the condensation from the system and establishing a partial vacuum therein during one portion of the cycle, then establishing a iiow of the steam from the source to fill the system during a succeeding portionof the cycle, and then cancelling the steam flow and permitting the system to heat the spaces during the remaining portion of the cycle.

8. The method of supplying steam from a source to a steam heating system for heating one or more enclosed spaces which involves, draining the condensation from the system and establishing avpartial vacuum therein during one period Cil of the cycle, then establishing a flow of steam from the source to'flll the system during a succeeding portion of the cycle, and then cancelling the steam flow and permitting the system to heat the spaces during the remaining portion of the cycle, the time interval of the last named period of the cycle being varied in response to variations in the temperature of atmosphere outside the spaces.

9. The method of supplying heat in periodic cycles from a, source to a plurality of subsidiary heating systems forming a major heating system arranged to -heat a plurality of enclosed spaces which involves, establishing independently timed ows of heat from the source to each subsidiary system in a predetermined sequence during the initial portion of the cycle and cancelling the heat flow thereto during the nal portion of the cycle, the time interval of the nal portion of the cycle being varied in response to the variations in the temperature of atmosphere outside the spaces.

10. The method ofsupplying heat inperiodic cycles from a source to a plurality of subsidiary heating systems forming a major heating system arranged to heat a plurality of enc`osed spaces Which involves, establishing independently timed flows of heat from the source to each subsidiary system in a predetermined sequence during the initial portion of the cycle and cancelling the heat ow thereto 'during the'nal portion of the cycle, the time interval of the independently timed ow periods being varied in response to variations in temperature of atmosphere outside the spaces.

ll. The method of supplying steam from a source to a plurality of subsidiary heating systems forming a major heating system which involves, periodically establishing ow of the steam from the source to the major system in inverse proportion to variations in temperature of the outside atmosphere, and during each periodic ow supplying the steam thereof successively to the subsidiary systems.

12. The method of heating a plurality of enclosed spaces heated by a plurality of subsidiary heating systems forminga major heating system which involves, establishing ilow of heat from a source to the major heating system in inve-rse proportion to variation in temperature of the atmosphere outside the spaces and .during each periodic ow apportioning the heat thereof successively to the subsidiary systems.

13. The method of supplying steam fro-m a source to a plurality of subsidiary heating systems forming a major heating system which involves, establishing flow. of steam from the source to the major system at predetermined and variable periods alternately with cancelling the ow for other predetermined and variable periods, and during each periodic flow apportioning the steam thereof successively to the subsidiary systems.

14. The method of heat regulation of buildings which are provided with valves for controlling individual heat supply risers, which consists in automatically alternating the supply of heat to adjacent risers according to a predetermined time interval.

15. The method of heat regulation of buildings which are provided With valves for controlling individual heat supply risers, which consists in automatically alternating the supply of heat to adjacent risers according to a predetermined time interval and continuously testing loutdoor temperatures and automatically varying said time intervals according to said outdoor temperature variations. 4

16. The method of heat regulation of buildings which are provided with valves for controlling individual heat supply risers, which consists in.

automatically alternating the supply of heat to adjacent risers according to a predetermined time interval during work hours and then automatically alternating the supply of heat to said vaccording toa predetermined time schedule, and

providing for control of groups from a central point.

18. The method of regulating the supply of heat to relatively large buildings having individual valve control for each heat supply riser and divided into a plurality of heating sections, with the controls for each section in closely adjacent relation, which consists in automatically alternating the supply of heat to adjacent risers according to a predetermined time schedule, and providing for controlof groups from a central point, and then automatically varying said time schedule according to outdoor temperatures.

19. The method of controlling the supply of steam from a common source toradiators located in a plurality of zones of a building or structures to be normally heated to substantially a uniform temperature while aiected by variations in outdoor temperature, which `comprises providing supplies of steam from the source to the radiators of each zone during spaced time intervals, the intervals of supply for one zone being interspaced with the intervals `of supply for another zone, and automatically controlling thermostatically in response to outdoor temperature variations, the relative lengths of said supply intervals as compared with the intervening periods, to regulate the rate of steam supply inversely in accordance with outdoor temperature changes, said intervals of supply normally being of sufficient frequency to enable 4substantially continuous maintenance of predetermined temperatures in the structures'heated.

20. The method of controlling the supply of steam from a common source to radiators located in a plurality of zones of va building or structures to be normally heated to substantially a uniform temperature While aiected by variations in outdoor temperature, which comprises providing supplies of ,steam from the source to the radiators of ea'ch zone during spaced time intervals, the intervals of supply for one zone being interspaced with the intervals of supply for another zone, and varying the rate of such supply of steam to each zone inversely in accordance with substantial changes of outdoor temperature, said intervals of supply normally being of sufficient frequency to enable substantially continuous maintenance of predetermined temperatures in the structures heated.

OSCAR A. ROSS. 

